In a project, I have embedded text steganography in a digital image and sent it to its receiver by means of electronic mail he received the image and decrypted the hidden text appropriately but I was wondering, Is it possible to get distorted while sending in digital mediums? If it is yes then what sort of distortion could take place?
Dear Quazi Saad,
While talking about digital image processing there comes an integrated part of it which is Noise. Noise is always presents in digital images during image acquisition, coding, transmission, and processing steps. It is very difficult to remove noise from the digital images without the prior knowledge of filtering techniques. In this tutorial, we together will get a brief overview of various noise and the filtering techniques of the same is described. These filters can be selected by analysis of the noise behavior. In this way, a complete and quantitative analysis of noise and their best suited filters will be presented over here. Definition of Image: Before going into Image processing let’s talk about image itself.
https://medium.com/image-vision/noise-in-digital-image-processing-55357c9fab71
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The most common are bit errors due to very low SNR. These errors occur both in the case of data transfers to the recipient and storage on data carriers. From this point of view, you can consider a data carrier as a form of communication, but it takes place in time (write today, read tomorrow), not over a distance.
This problem is seen at the level of communication protocols, firmware, and sometimes the files themselves. Data integrity is secured by ECC codes and checksums. Therefore, despite the fact that the problem is common, we rarely experience it in practice. If you compare the contents of both files in the hex-editor or calculate the hash for them, they should be identical, but if you want to analyze the signal transmitted during the transmission, the signal captured from the disk's magnetic heads block, or the contents of the NAND chips, you will notice slight differences. And as long as the number of these errors does not exceed the capabilities of the ECC codes, you as a computer user will not notice these errors.
With the CBC mode of encryption, a transmission error will cause whole block of plaintext (usually 16 bytes) to be totally garbled. When using a CTR mode, a single bit error in the input leads to a single bit error in the output. This could lead to a garbled area in the image, or to a total decode failure if it happens in some header.
Well, you often get to choose how the image is conveyed, and many forms of conveyance maintain integrity at least in the network protocols if not end to end.
bit rot is always a problem while an image is in storage. you might run out of disk space and end up with truncated or missing images, though, particularly if you are transferring a large number of images onto or via a small device using a stupid app and ignoring diagnostics.
many archiving formats support some form of integrity checking on metadata and on data. e.g. 7z, rar, and zip. see https://en.wikipedia.org/wiki/List_of_archive_formats#Comparison
and
https://en.wikipedia.org/wiki/Data_corruption
for more info.
even without a hash or crc to verify integrity, you should be able to visually detect truncation within an image, and a few low order bits clobbered are unlikely to affect the visual perception of an image. (of course, they will change the hash value completely, which will make traditional duplicate detection fail.)
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